What are the ingredients in making a mosquito repellent coil?

I have in front of me four different packets of coils.





The ingredients stated on the boxes vary, and are as follows, but are not very clear:





1. D-Allethrin 0.3 %; other ingredients 99.7 %.





2. Pyrethrins l,ll, 0.25 %; other ingredients 99.75 %





3. and 4. Contains Citronella Oil.